Sunglasses, the nominal vertex value should be 0.00D, lens manufacturing deviation or lens and frame assembly does not match, are likely to produce vertex sunglasses
Deviation (that is, with or positive or negative vertex), if beyond a certain range, the wearer may feel like deformation, serious will affect the wearer's visual health. Corresponding to GB10810.1 "glasses lens part 1: single and multifocal lenses" national standard Table 1 requirements, the spherical vertex tolerance of ± 0.12D; cylindrical vertex tolerance of ± 0.09D.